3D camera smooth arcs movement with null object

Hi guys, I'm trying to animate 3D camera via null object but I can not see motion path on null object 3D layer. I want to curve a little null object spatial movement but I do not know how. Also, graph editor doesn't offer any solution. Any idea how to solve this or I have to animate my 3D camera layer directly? I have followed an advice that animating camera is easier via null object but I really do not know what are advantages and disadvantages of that approach... Any idea? Thanks in advance!